Designing Excess Electron Compounds by Substituting Alkali Metals to a Small and Versatile Tetracyclic Framework: A Theoretical Perspective

Santosh Kumar Yadav; Snehasis Bhunia; Rajneesh Kumar; Ritu Seth; Ajeet Singh

doi:10.1021/acsomega.2c07743

Designing Excess Electron Compounds by Substituting Alkali Metals to a Small and Versatile Tetracyclic Framework: A Theoretical Perspective

ACS Omega. 2023 Feb 16;8(8):7978-7988. doi: 10.1021/acsomega.2c07743. eCollection 2023 Feb 28.

Authors

Santosh Kumar Yadav¹, Snehasis Bhunia², Rajneesh Kumar¹, Ritu Seth¹, Ajeet Singh¹

Affiliations

¹ Department of Chemistry, Prof. Rajendra Singh (Rajju Bhaiya) Institute of Physical Sciences for Study and Research, V.B.S. Purvanchal University, Jaunpur 222003, India.
² Department of Chemistry, National Taiwan University, No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan (R.O.C.).

Abstract

Organic compound-based nonlinear optical (NLO) materials have sparked a lot of attention due to their multitude of applications and shorter optical response times than those of inorganic NLO materials. In the present investigation, we designed exo-exo-tetracyclo[6.2.1.1^3,6.0^2,7]dodecane (TCD) derivatives, which were obtained by replacing H atoms of methylene bridge carbon with alkali metals (Li, Na, and K). It was observed that upon the substitution of alkali metals at bridging CH₂ carbon, absorption within the visible region occurred. Moving from 1 to 7 derivatives, the maximum absorption wavelength of the complexes exhibited a red shift. The designed molecules showed a high degree of intramolecular charge transfer (ICT) and excess electrons in nature, which were responsible for rapid optical response time and significant large molecular (hyper)polarizability. Calculated trends also inferred that the crucial transition energy decreased in order that also played a key role in the higher nonlinear optical response. Furthermore, to examine the effect of the structure/property relationship on the nonlinear optical properties of these investigated compounds (1-7), we calculated the density of state (DOS), transition density matrix (TDM), and frontier molecular orbitals (FMOs). The largest first static hyperpolarizability (β_tot) of TCD derivative 7 was 72059 au, which was 43 times greater than that of the prototype p-nitroaniline (β_tot = 1675 au).